Coastal Inundation

The maps can be viewed via the *Hawke’s Bay Hazard Portal here. 

*We are currently experiencing high levels of traffic to the Hawke's Bay Hazard Portal, which may result in some disruptions when trying to access the service. If you experience delays accessing the maps, please try again later.

You can also view mapping with more detailed representation of inundation depth here.

Coastal inundation is the flooding of low-lying coastal land with seawater during tidal storms. This can happen when extreme weather events lead to storm surges, causing elevated wave crest height. Coastal inundation is likely to increase through future sea level rise caused by climate change

The maps were produced as part of the Coastal Inundation: Tangoio to Clifton report commissioned jointly by Napier City Council, Hastings District Council and Hawke’s Bay Regional Council to better inform the setting of building floor heights in areas at risk of coastal inundation.

Councils are required to manage natural hazard risks under different pieces of legislation, including the Resource Management Act 1991, Building Act 2004, Local Government Act 2002, and Civil Defence and Emergency Management Act 2002.

Under the New Zealand Coastal Policy Statement 2010, councils are also required to help prepare communities for the impacts of climate change, including ongoing changes to weather patterns and rising sea levels.

The maps show areas within our city, over the next 75 years and beyond, that could potentially flood from seawater during an unlikely extreme weather event.

The maps are modelled on what could happen in year 2100 with ‘worst case scenario’ sea level rise during a 2% annual exceedance probability (AEP) or a 1% annual exceedance probability (AEP) storm surge event, where the sea overtops the shoreline and floods the land.

It is very important to understand the maps do not account for current mechanical mitigations such as pumps, and do not account for any future work Council may undertake like raising beach crest heights.

Annual Exceedance Probability (AEP) describes the likelihood of reaching or exceeding a flooding level in any calendar year, usually expressed as a percentage. For example, a flood level with a 1% AEP has a 1% chance (or 1 in 100 chance) of occurring in any year and a 2% AEP has a 2% chance (or 1 in 50 chance) of occurring in any year.

The maps were developed as part of the Coastal Inundation: Tangoio to Clifton report (dated November 2023). This was prepared by Tonkin & Taylor Ltd. and peer reviewed by NIWA.

The coastal inundation maps have been produced in line with best practice using current techniques. Coastal mapping is a complex and detailed process that relies on the best available data as well as various assumptions made by specialists in the area, so it can never be completely accurate. The maps are projections that could change over time.

Councils have an obligation to make hazard information they hold available under the Local Government and Official Information and Meetings Act 1987. In the future, for a property potentially affected by coastal inundation, Land Information Memorandum (LIM) will note this.

A Land Information Memorandum (LIM) is a summary of information about a property (at the point in time at which it is requested) held by the Council. For both sellers and buyers, a LIM may answer some important questions about the land or any buildings that are on the property. A LIM can include building permits, consents and activity licences information as well as land and property-related information and services. LIM’s can help people to make informed decisions when buying, building, repairing or investing in property.

Under the Local Government Official Information and Meetings Act 1987, council is required to make LIM information available to any interested party. This includes any information that Council may hold in relation to natural hazards where council is required to show all known natural hazards information, that may potentially occur.

Section 44A of the Local Government Official Information and Meetings Act 1987 (LGOIMA) specifies that information identifying each special feature or characteristic of the land is to be included in the LIM if they are known to Council but are not apparent from the district plan. Special features or characteristics of the land may include but are not limited to potential erosion, falling debris, subsidence, flooding or inundation.

In this instance, Council is required to give anyone who requests a LIM:

• The range of information it holds on inundation, against varying sea level rise scenarios;
• Where applicants can find these reports;
• Where applicants can view the information using our mapping system.

There is no action required by you regarding your updated LIM. The letter or email you should have received is to let you know about the new notation(s) that have come about following the assessment, which we are legally obliged to add to your LIM, as outlined above.

The Building Act 2004 requires consideration of whether the land is likely to be subject to one or more natural hazards. When a proposed building or property falls fully or partly within the inundation zones, building consent applications will be subject to an assessment under sections 71 and 72 of the Building Act 2004. Please contact Napier City Council’s Building Department at dutybuilder@napier.govt.nz to determine the required process and scenarios to be used in any building consent application.

Councils set minimum floor levels to protect buildings from the risk of flooding. If you are building, rebuilding or extending within the coastal inundation zones identified in the mapping, your building may need to be built to the new floor level requirement.

The implications will differ from property to property, depending on things like elevation. Anyone looking to build or renovate should be aware of the natural hazard provisions in sections 71-73 of the Building Act 2004.

In accordance with the Building Act, the modelling and data provided in the report will inform decisions made by councils on consent applications for properties within coastal inundation zones.

New floor height levels will only apply to new builds and renovations/extensions.

Councils are unable to advise on any effect this information may have on property values or insurance. It is important to seek professional advice from a property valuation or insurance professional with any questions regarding these matters.

Under the Local Government Official Information and Meetings Act 1987, councils have an obligation to make natural hazards information available. The data used to prepare the maps will be applied on Land Information Memorandum (LIMs). When you’re selling a property, you and your agent are legally obliged to share all relevant information about it to buyers. It’s also important that potential buyers do their own due diligence on any property they wish to buy.

The modelling and data presented in the report will inform the following activities:

• Consideration of building consent applications under the Building Act 2004
• Consideration of subdivision consent applications under the Resource Management Act 1991
• Future land use planning
• Infrastructure planning
• Producing Land Information Memoranda (LIM)

The modelling and data provided in the report will help councils plan, prepare and inform future investments in infrastructure along the coastline and within coastal communities.

There are already significant mitigations in place protecting Napier’s coastal communities from storm surge events, including:

• Raised gravel barriers along our beaches designed to stop seawater overtopping. Raising these gravel barriers is an effective way of managing coastal inundation in the future.
• Stormwater systems including pump stations with supporting generators intended to drain ponded water. This applies to some areas such as Te Awa.

By adopting a combination of approaches, councils enhance the resilience of coastal areas against inundation and better protect communities and infrastructure from the impacts of rising sea levels and other coastal hazards. Some examples of possible approaches are:

• Construction of seawalls, levees, and barriers to protect vulnerable areas from flooding and storm surges;
• Nature-based approaches such as restoring wetlands to act as natural buffers;
• Renourishment of beaches to maintain and enhance natural defences;
• Raise critical infrastructure, roads, and buildings in vulnerable areas to reduce flood risk.

• A note will be applied to any LIM that is requested from 14 December 2023 stating that the property is subject to a coastal inundation hazard.
• The 2% data will be used when assessing building consent applications and you may be required to build to a certain minimum floor height for your proposed building work to be compliant with the New Zealand Building Code.
• Where a building consent is required, the 1% data will also be used to inform decision-making under s 71-73 of the Building Act 2004 which relate to building on land that is subject to, or likely subject to, a natural hazard.

• The data will be used when assessing building consent applications and you may be required to build to a certain minimum floor height for your building work to be compliant with the New Zealand Building Code.
• A LIM note will be applied to the property file.